The effects of elevated hemoglobin A1c in patients with type 2 diabetes mellitus on dental implants: Survival and stability at one year

Background.The authors conducted a prospective cohort study to determine whether poor glycemic control is a contraindication to implant therapy in patients with type 2 diabetes.

Methods. The study sample consisted of 117 edentulous patients, each of whom received two mandibular implants, for a total of 234 implants. Implant-retained mandibular overdentures were loaded after a four-month healing period and followed up for an additional one year. The authors assessed implant survival and stability (by means of resonance frequency analysis) relative to glycated hemoglobin A_1c (HbA_1c) levels, with baseline levels up to 11.1 percent and levels as high as 13.3 percent over one year.

Results. Implant survival rates for 110 of 117 patients who were followed up for one year after loading were 99.0 percent, 98.9 percent and 100 percent, respectively, for patients who did not have diabetes (n = 47), those with well-controlled diabetes (n = 44) and those with poorly controlled diabetes (n = 19). The authors considered the seven patients lost to follow-up as having had failed implants; consequently, their conservative estimates of survival rates in the three groups were 93.0 percent, 92.6 percent and 95.0 percent (P = .6510). Two implants failed at four weeks, one in the nondiabetes group and the other in the well-controlled diabetes group. Delays in implant stabilization were related directly to poor glycemic control.

Conclusions. The results of this study indicate that elevated HbA_1c levels in patients with type 2 diabetes were not associated with altered implant survival one year after loading. However, alterations in early bone healing and implant stability were associated with hyperglycemia. Practical Implications. Within the clinical parameters of this study, the findings indicate likely implant success among patients with type 2 diabetes who lacked good glycemic control. Further investigation, including longer-term evaluation, is needed.